49 results about "Triangular element" patented technology

The invention provides a coherent signal arrival direction estimation method and device based on a deep convolutional network, and belongs to the field of array signal processing. The method comprises the following steps: receiving a to-be-detected signal containing a coherent signal by using a uniform linear array antenna to obtain an array receiving data matrix and extract a covariance matrix; forming an input feature vector by right upper triangular elements divided from a diagonal line in the covariance matrix, inputting the input feature vector into a covariance estimation model formed by a deep convolutional network, obtaining an estimation value of the right upper triangular elements under an ideal incoherent condition, and reconstructing the estimation value to obtain a covariance matrix estimation value; and performing characteristic decomposition on the covariance matrix estimation value, and generating a spatial spectrum by using a MUSIC algorithm to obtain an estimation result of the signal arrival direction. According to the method, the noise-containing mixed signal covariance matrix is mapped into the ideal incoherent noise-free signal covariance matrix through a physical constraint supervised learning framework, so that the estimation precision and robustness of the MUSIC algorithm in a coherent scene are improved.

The invention provides a cavity target infrared characteristic calculation ray tracing method, and belongs to the technical field of infrared tracing. The method comprises the following steps: importing a CFD data source; a cuboid space grid is generated, and CFD data space distribution is interpolated and reconstructed; a target material and temperature parameters are set; determining the position of a detector and forming a detection situation relationship; gridding a detection space in the transverse direction and the longitudinal direction at the position of the cavity object to form a field pixel space; constructing a reverse ray vector direction, and counting self reflection and reflection radiation of each triangular infinitesimal according to a recursive iteration mode; reconstructing a broadband spectral reflection coefficient according to the narrowband BRDF model and the broadband spectral emissivity; and determining the reflection direction of the infrared rays based on a bidirectional reflection distribution model to realize ray tracing. According to the invention, the control of any ray tracing depth can be realized, the intersection judgment process is greatly simplified, and the problem of high-efficiency and high-precision calculation of the cavity and the low-emission material is effectively solved.

The invention belongs to the technical field of airplane structure strength digital twinborn model construction, and particularly relates to an airplane structure finite element calculation result data noise reduction method, which comprises the following steps: step 1, preliminarily identifying deformity units including triangular units and high slenderness ratio units; identifying the triangular units based on the continuity of the node numbers; identifying a high slenderness ratio unit based on the side length; 2, defining a stress concentration area, and removing units in the stress concentration area from the deformed units; defining a stress concentration region including a hole edge, a fillet, a boundary constraint position and a region where a concentrated load applying position is located; 3, calculating the gradient of the deformity units, and removing units in a real physical gradient field from the deformity units; step 4, carrying out noise reduction processing on the calculated value of the malformation unit; and smoothing the calculated value of the malformed unit, or removing the calculated value of the malformed unit.

The invention discloses a cylindrical surface or similar cylindrical surface homeomorphic parameterization method for grid redivision, which comprises the following steps: carrying out feature recognition on a geometric surface to be parameterized, and if the geometric surface has the features of the cylindrical surface, defining the inner and outer boundaries of the complete cylindrical surface; performing parameterization processing of conformal mapping on all triangular units of the grid according to the new boundary; and checking and correcting the quality of the parameter plane target grid. The defect that the cylindrical surface cannot be directly unfolded to a two-dimensional parameter plane under the condition that the cylindrical surface is not sheared off is overcome, the characteristics of the cylindrical surface can be kept when the method is applied to grid re-division, and therefore reasonable deformation of grids can be achieved, the defects of large grid distortion, grid self-intersection and the like are overcome, and the user-friendly purpose is finally achieved.

The invention relates to the technical field of numerical simulation of rock dynamics, in particular to a numerical simulation method and system for the whole process of ore rock fracture based on FDEM impact loads.The method comprises the steps that a continuous medium structure is discretized into a finite element network composed of triangular units through FDEM, and an ore rock impact test model is constructed; setting material parameters and impact speed boundary conditions according to the ore rock impact test model; a normal contact force calculation model and a tangential contact force calculation model are established according to material parameters and impact speed boundary conditions, and coordinates and speed updating results of triangular unit nodes are obtained in combination with the Newton second law and the calculation models; and performing visual analysis based on the coordinate and speed updating result, and outputting crack propagation, stress field and energy evolution results under the impact load. The method can accurately simulate the crack propagation, the fracture mode and the energy evolution law of the ore rock under the impact load, quantitatively researches the crushing characteristics and the energy evolution law of the ore rock, and provides a calculation method for the research of the crushing mechanism of the ore rock.

The invention provides a direct-current voltage drop calculation method, computer equipment and a storage medium. The method comprises the following steps: acquiring a design file of a PCB (Printed Circuit Board) and setting initial simulation parameters; performing spatial discretization processing on a metal layer of the PCB on a two-dimensional plane according to the geometric layout information to generate a grid composed of triangular units; enabling packaging nodes in the initial simulation parameters to correspond to grid nodes, and calculating a conductance value of an edge of each triangular unit when the edge is equivalent to a linear resistor; enabling a non-current source device which cannot be represented by linear admittance in the PCB to be equivalent to an external circuit, enabling the edge of the triangular unit to be equivalent to a linear resistor in the external circuit, and constructing a circuit network model; and constructing a linear equation set matrix according to the circuit network model, and solving the linear equation set matrix to obtain the DC voltage drop of the PCB. According to the scheme, the requirement for computing resources can be remarkably reduced, the computing speed is increased, the simulation precision is ensured, and an accurate direct-current voltage drop computing result is provided for power supply integrity analysis.

The present invention discloses a method for calculating the harmonic response of a magneto-electro-elastic structure using enhanced overlapping triangular units, which relates to the technical field of magneto-electro-elastic intelligent materials. In the process of constructing a local enhanced interpolation basis function, a composite basis function consisting of a Lagrange polynomial basis function and a plane wave basis function is used for construction; in the process of constructing a local numerical approximation, a weighted function is constructed by introducing a mid-edge node in each enhanced overlapping triangular unit, and numerical interpolation is completed under the premise of satisfying the unit decomposition characteristics. Based on the numerical interpolation, a dynamic matrix control equation of the magneto-electro-elastic structure is established, and an enhanced overlapping finite element numerical model of the solver dynamic response is obtained. After applying appropriate boundary conditions and external excitations, a high-precision prediction of the harmonic response of the magneto-electro-elastic structure can be completed.

The present invention provides an imaging method for the singular mode vibration mode of FBAR based on the semi - analytical finite element theory, including the following steps: Step S1, constructing a semi - analytical finite element formulation of a FBAR with a complex electrode configuration; Step S2, using triangular elements to mesh the upper surface of the FBAR to obtain the coordinates of three nodes in each mesh element; Step S3, determining the interpolation shape function, stiffness matrix and mass matrix of each mesh element according to the node coordinates; Based on the semi - analytical finite element theory, the present invention characterizes the vibration mode of a three - dimensional FBAR at ultra - high frequencies, reduces the three - dimensional modal vibration imaging of a three - dimensional FBAR device to two - dimensional planar imaging. The simplification of the element type and the substantial reduction in the number of elements make the imaging technology provided by the present invention have a lower time cost. At the same time, it does not require various parameter settings and post - processing in commercial finite element software, realizing fast and quantitative imaging of the FBAR vibration mode.

The invention relates to an antenna grid installation method for antenna layout design, and belongs to the technical field of electromagnetic compatibility and antennae, and the method comprises the steps: importing a grid model file of a large-size platform and an antenna, and reading a grid model to obtain a point coordinate list and a triangular unit list of the platform and the antenna; reading a starting point coordinate, a termination point coordinate, a voltage amplitude and a phase of an excitation voltage source of the antenna; establishing an antenna initial coordinate system, setting the main radiation direction of the antenna to establish a surface local coordinate system on the surface of the platform, and performing point matching on the model; and mounting the antenna grid model and the excitation source on the surface of the platform. According to the method, direct processing of complex grids is supported, limitation of traditional CAD modeling is broken through, subdivided discrete grids can be directly operated, and model reconstruction is avoided; through normal offset control and local coordinate system mapping, the normal function of the installed antenna is ensured, and the installation efficiency can be significantly improved on the premise of maintaining high-precision electromagnetic characteristics.

The invention belongs to the technical field of three-dimensional discrete element loading, and aims to solve the technical problems that a hexagonal unit is mostly adopted in the current discrete element three-axis undrained loading and volume monitoring process, adjacent particle pointers need to be repeatedly read through id numbers, a large amount of vector operation is carried out, and the computing power is wasted. The invention provides a three-dimensional discrete element flexible undrained loading method based on dynamic geometry, and the method comprises the steps: simplifying a hexagonal basic unit in a conventional flexible film loading process into a simpler triangular unit through introducing a geometry unit; and in combination with the specific area and normal vector extraction advantages of the geometer poly unit, the load application and volume dynamic monitoring process in the non-drainage loading process of the flexible film is effectively simplified, and the related research of the discrete element three-dimensional flexible film is promoted.

The present application relates to the technical field of machining, in particular to a free curved surface machining track generation method based on conformal mapping, which first selects an input three-dimensional triangular mesh curved surface; then uses a boundary-first unfolding algorithm to unfold it into a two-dimensional parameter domain triangular mesh plane, so that the obtained two-dimensional parameter domain triangular mesh plane is rectangular, and the deformation generated by the mapping is minimal; the next step is to deform the shape of the two-dimensional parameter domain triangular mesh plane to the size of the design area; after a designer plans a two-dimensional machining track on the design area, i.e. the deformed two-dimensional parameter domain triangular mesh plane, the machining track is discretized into a plurality of machining track points, and the barycentric coordinates of the machining track points in the corresponding triangular elements of the two-dimensional parameter domain triangular mesh plane are calculated, and finally the machining track points are inversely mapped onto the input triangular mesh curved surface, so that the input three-dimensional machining track is obtained. The present application solves the shortcomings of the prior art and can adaptively generate a corresponding spatial machining track on a three-dimensional curved surface.

The invention relates to a microwave thermal imaging-based stealth coating damage area three-dimensional reconstruction method, which belongs to the technical field of measurement, solves the problem of insufficient reconstruction accuracy of stealth coating damage in the prior art, and comprises the following steps: S1, carrying out microwave thermal imaging treatment on a stealth coating with damage to obtain an infrared temperature cloud picture of the surface of the stealth coating; s2, processing to obtain a to-be-reconstructed invisible coating damage area; s3, dividing a to-be-reconstructed invisible coating damage area into triangular surface element grids of a plurality of planes; s4, the center of each triangular surface element grid obtained through division is calculated, the center temperature of each triangular surface element grid is obtained, and the generalized reflectivity of the center of each triangular surface element grid is calculated; s5, calculating the depth of the center of each triangular surface element grid; s6, constructing a triangular body element by combining the depth of the center of each triangular surface element grid; and S7, combining all the triangular voxels to obtain the damage area of the three-dimensional reconstructed stealth coating.

The technical solution of the present invention provides a method for generating a three-dimensional signed distance field based on a characteristic polyhedron of an object's surface mesh. The method comprises constructing a characteristic polyhedron from surface features derived from triangular elements in the object's STL surface mesh file; and generating a narrowband signed distance field from the characteristic polyhedron. The method provided by the present invention is not limited by the geometric complexity of the object or the resolution of the domain. The method can construct the characteristic polyhedron and its boundary volume for generating the signed distance field from the surface features of the triangular elements in the STL surface mesh file, directly using the modeling file, shortening the process. The characteristic polyhedron and its boundary volume data are processed by a specific algorithm to achieve accurate generation of the narrowband signed distance field in a method that efficiently saves computing resources, optimizes storage space and generation time, and reduces computational difficulty.

The application discloses a kind of multivariate time series unsupervised dimension reduction method based on global-local divergence, it includes the following steps: S1, the covariance matrix of multivariate time series is calculated, the upper triangular element of covariance matrix is extracted, it is combined as feature sequence, obtain the feature set Fea of multivariate time series={f i |i=1,2,…,n};S2, using k near neighbor and Euclid Distance (Euclid Distance, ED) measure is established neighborhood set N k (f i )={f j |j=1,2,…,k};S3, after finding the neighborhood of each sample point, the neighborhood center sequence m i Of each feature sequence f i In feature set is calculated;S4, with the neighborhood variance of sample point after projection, local divergence is characterized.First, the variance of each sample point neighborhood set after projection is calculated, then the sum of the accumulation of these variances is obtained, to obtain local divergence;S5, according to the field center point obtained in step S3, the variance of field center point is calculated to obtain global variance.Finally, the low-dimensional projection sequence obtained by the experimental result shows that the method can represent original MTS, and obvious dimension reduction is realized.

The invention provides an electromagnetic surface wave transmission method based on wave-absorbing coating damage three-dimensional reconstruction, and belongs to the technical field of measurement, and the method comprises the following steps: carrying out microwave heating treatment on a damaged wave-absorbing coating sample, and carrying out computer treatment to obtain a surface temperature cloud picture of the sample; extracting an area of which the surface temperature of the wave-absorbing coating is higher than the test environment temperature from the surface temperature cloud picture; performing triangular surface grid division on the extracted region, and combining all triangular volume elements to realize three-dimensional reconstruction of the damaged region of the wave-absorbing coating; constructing a surface wave propagation method based on a dispersion equation; a dispersion equation is utilized to analyze transmission of surface waves in the three-dimensional reconstruction model of the damaged area of the wave-absorbing coating, the influence of the thickness of a triangular voxel and electromagnetic parameters of a combined model of the triangular voxel on a surface wave attenuation constant is discussed, and a surface wave attenuation constant model based on three-dimensional reconstruction of the damaged area of the wave-absorbing coating is constructed. The method provides a theoretical basis for damage evaluation of the wave-absorbing coating of the aircraft.

This invention discloses a lightweight deep neural network array direction finding method based on data redundancy removal, which solves the problem that the traditional RDNN direction finding method has a large number of deep neural network nodes and cannot achieve network lightweighting. The method performs redundancy removal operation on the upper triangular elements of the covariance matrix, simplifies the number of subsequent hidden layer nodes, reduces the computational complexity of the model, and ensures that the direction finding accuracy of the model is not lost, thus realizing high-precision direction finding of lightweight deep neural networks.

The application discloses a cylindrical surface or cylindrical surface-like homeomorphism parameterization method for mesh redivision, and comprises the following steps: feature recognition is performed on a geometric surface to be parameterized; if the geometric surface has the feature of a cylindrical surface, the inner and outer boundaries of a complete cylindrical surface are defined; parameterization processing of conformal mapping of all triangular elements of the mesh is performed according to the new boundaries; and the quality of the target mesh of the parameter plane is checked and corrected. The application makes up for the deficiency that the cylindrical surface cannot be directly unfolded to a two-dimensional parameter plane without being cut, can keep the feature of the cylindrical surface when applied to mesh redivision, can achieve reasonable deformation of the mesh, and can avoid the disadvantages of large mesh distortion and mesh self-intersection, and finally achieves the purpose of user friendliness.

The invention discloses a two-dimensional interferometer direction finding method based on a multi-frequency sparse area array. The method mainly solves the problems that in the prior art, the array arrangement space size is limited, and the two-dimensional DOA estimation precision is poor in a low signal-to-noise ratio scene. Comprising the following steps: 1) constructing a sparse plane physical array; 2) carrying out channelization processing on the broadband signal received by the antenna; 3) acquiring a vector signal model of the mapped channel by taking the center frequency of the Lth channel signal as a reference; 4) selecting effective channel data from L-1 channels, mapping all the center frequencies of the effective channel data to the center frequency of the Lth channel signal, and combining the signals; 5) calculating the covariance of the signal, and extracting the phase of a triangular element on the matrix; and 6) selecting a phase difference corresponding to the virtual baseline from the extracted phases, and realizing two-dimensional interferometer unambiguous direction finding by using a long and short baseline method. According to the method, two-dimensional DOA high-precision estimation can be effectively realized, and the method can be used for realizing two-dimensional direction finding of a target by a small unmanned aerial vehicle in a low-signal-to-noise-ratio environment.

The present invention belongs to the field of marine surveying and mapping technology, and discloses a method for mapping land and water terrain using unmanned aerial vehicle laser / shipborne multi-beam data. The method roughly extracts data overlap areas through virtual grids, and finely extracts overlap areas using an alpha-shape algorithm to obtain boundary points, and removes edge triangles in an irregular triangulated network constructed by unmanned aerial vehicle laser bathymetry data and shipborne multi-beam bathymetry data; calculates vertex normal vectors, uses the vertex tangent plane of the multi-beam irregular triangulated network as a registration primitive, and performs weight distribution based on the distance from point to vertex, and performs rough registration through an ICP registration algorithm from point to plane; constructs a fine registration model based on point-to-plane distance, and eliminates elevation differences in overlapping areas by minimizing the normal distance from unmanned aerial vehicle laser bathymetry points to multi-beam bathymetry triangle face elements. The point cloud fusion model of the present invention is used for processing, and the phenomenon of inconsistent elevations of point clouds from different sources in overlapping areas is effectively improved, and underwater terrain data fusion is realized.

The embodiment of the invention provides an STL (Standard Template Library) grid region division and re-subdivision method and device based on feature preservation. The method comprises the following steps: acquiring an initial grid container; subdividing triangular units in the initial grid container based on a longest edge bisection algorithm; the subdivided triangular units are stored in a subdivision grid container; feature boundary extraction is carried out on triangular units in the subdivided grid container in a dihedral angle threshold value judgment mode; on the basis of the feature edges of the triangular units in the subdivided grid container, performing feature curved surface division on the triangular units in the subdivided grid container through a curved surface division algorithm based on depth-first search to obtain a plurality of feature curved surfaces; and through harmonic mapping and an AFT-Delaunay method, parameterization is carried out on the characteristic curved surface, and mesh generation of the characteristic curved surface is completed. In this way, key geometric features such as sharp edges and ridges of the model can be accurately recognized, the dependence on the initial grid quality is reduced, and the generated grid quality is greatly improved.

The application relates to a method for generating a body grid based on radial growth of a cylindrical surface grid, in the field of electromagnetic engineering, and the method comprises the following steps: reading cylindrical surface grid data, including a point list P containing three-dimensional coordinates of N p points, a triangular element list E containing vertex indexes of E e triangular elements, and an element material list M; screening target elements through material matching; establishing a local coordinate system satisfying the right-hand rule and the orthogonal normalization condition of a vector, and performing coordinate transformation; performing radial mapping on the vertices of the screened elements; inversely transforming the mapped points to a world coordinate system; and generating a body grid, and converting a six-vertex triangular prism into three four-vertex tetrahedron elements by using a topological decomposition method. The electromagnetic calculation precision is improved: in electromagnetic field design calculation, the cylindrical radial grid growth technology makes the grid resolution in a strong field area multiply, and the calculation error of a resonance frequency is less than or equal to 0.3%.

The application discloses a method for implanting a large deformation plastic element based on FDEM in a non-rotating reference system, which comprises the following steps: obtaining a deformation rate in a rotating configuration and a rotation matrix based on the node coordinates of a triangular element; obtaining the deformation rate in a non-rotating configuration based on the deformation rate in the rotating configuration and the rotation matrix; determining an elastic trial stress, determining a material state in combination with a yield function, obtaining a true stress, and performing rotation mapping of an original reference configuration to obtain a true Cauchy stress; according to FDEM calculation, calculating contact force and force caused by cohesive force elements, and then uniformly converting the contact force and the force into node force; updating the node velocity and the position in the current time step through Newton's second law; and entering the next time step. The application introduces the calculation of a stress tensor in a non-rotating reference system, rotates the stress tensor, maps the stress tensor to the original reference system, and realizes the accurate simulation of plastic behavior in the wired-discrete element in combination with a yield function and a plastic flow rule.

The application provides a coarse-grained aggregate mechanical behavior continuous-discontinuous numerical calculation method, including: establishing a numerical model of coarse-grained aggregate, the numerical model including a constant strain elastic triangular element and an initial thicknessless cohesive force element distributed along the boundary of the triangular element; determining the constitutive relation of the cohesive force element in the numerical model under a continuous deformation analysis framework; determining the contact relation between discrete triangular elements in the numerical model under a discontinuous deformation analysis framework; obtaining a continuous-discontinuous coupling model of the coarse-grained aggregate based on the determined constitutive relation and contact relation, inputting boundary constraint conditions and external loads into the continuous-discontinuous coupling model according to actual working conditions, and performing simulation calculation to obtain the mechanical properties and deformation failure forms of the coarse-grained aggregate under external loads. The application establishes a corresponding numerical model through digital image analysis and recognition technology, completes continuous-discontinuous coupling calculation of the mechanical behavior of coarse-grained aggregate, and takes into account solving accuracy and calculation efficiency.

The invention discloses a numerical calculation method for simulating two-dimensional space crack propagation and a related device, and relates to the technical field of computational mechanics, and the method comprises the following steps: obtaining an overall crack solving region and a crack tip region of a cantilever beam; establishing a transition area based on the crack overall area and the crack tip area; constructing a transition region basis function based on the transition region; based on the transition area primary function, the overall area primary function and the crack tip area primary function, solving the transition area, the overall area and the crack tip area to obtain a two-dimensional crack propagation result; the overall area primary function is a finite element primary function obtained after linear quadrilateral or triangular unit discretization; the primary function of the crack tip area is a B spline primary function; the two-dimensional crack propagation result comprises an overall displacement solution, a crack tip area displacement solution and a transition area displacement solution. According to the method, the numerical value of two-dimensional crack propagation can be accurately and stably simulated.

This application discloses a two-dimensional DC electric field forward modeling method, apparatus, electronic device, dielectric, and product. The method includes: taking the variational problem of a two-dimensional wavenumber domain point source DC electric field as the research object; dividing the model region of the dielectric model into several triangular elements and expanding the model region with a sparse mesh; reading the conductivity and potential of the principal nodes in each triangular element, and representing the conductivity and potential with quadratic interpolation shape functions to obtain a discrete model; constructing a system of linear equations based on the discrete model and the coefficient matrix of each triangular element; solving the system of linear equations to obtain the wavenumber domain forward modeling result; and performing an inverse Fourier transform on the forward modeling result to obtain the spatial domain electric field potential. The method increases the number of nodes in the mesh during model region meshing, reduces computation time by expanding the model, and utilizes more node property information through biquadratic interpolation of conductivity and potential within the mesh, thereby improving the accuracy of the two-dimensional DC electric field forward modeling fitting.

This invention provides a quasi-regular double-six discontinuous triangular mesh construction method for searching potential slope sliding surfaces, comprising: iteratively generating a quasi-regular initial triangular mesh adapted to the slope model boundary; locally dividing into six meshes to generate a six-directional arrayed topological mesh; constructing a data format of six-node triangular elements and high-order discontinuities; and solving the potential slope sliding surface using a second-order cone programming model. This invention adapts to the geometric boundaries of discrete slope models and meets the special requirements of the quasi-regular double-six discontinuous triangular mesh, forming a six-directional continuous discontinuous mesh structure within any small region. Furthermore, the double-six discontinuous mesh can be further pre-defined with local partitions, reducing resource consumption of mesh elements in non-critical areas. Applied to the upper limit finite element method of limit analysis, it achieves high-precision searching of potential slope sliding surfaces through rapid solving of the second-order cone programming problem, thus reducing computational burden while maintaining search accuracy.

This invention discloses a parameterization method for non-convex domains of complex surfaces generated by edge suppression. The method includes: performing edge suppression processing on an industrial part model to extract an initial 3D network of the geometric surfaces obtained after edge suppression; performing two-point constraint conformal parameterization on the triangular elements in the initial 3D network; detecting and removing self-intersections, parameterizing again, and repeating this step until no self-intersection regions exist; detecting and correcting element normal vector flips, parameterizing again, and repeating this step until no element normal vector flips exist, at which point the parameterization ends. This invention achieves non-convex domain parameterization of spatial triangular networks of complex surfaces generated by edge suppression. By fully considering the curvature characteristics of the 3D surface, it avoids the drawbacks of generating large distorted meshes, and can meet the mesh quality requirements of subsequent numerical calculations for mechanical analysis.

The application provides an electromagnetic surface wave transmission method based on three-dimensional reconstruction of damage of a wave-absorbing coating, and belongs to the technical field of measurement, and comprises the following steps: microwave heating treatment is performed on a wave-absorbing coating sample with damage, and a surface temperature cloud chart of the sample is obtained through computer processing; a region with a surface temperature of the wave-absorbing coating higher than a test environment temperature is extracted from the surface temperature cloud chart; the extracted region is subjected to triangular face mesh division, and all triangular elements are combined to realize three-dimensional reconstruction of the damage region of the wave-absorbing coating; a surface wave propagation method based on a dispersion equation is constructed; the transmission of surface waves in the three-dimensional reconstruction model of the damage region of the wave-absorbing coating is analyzed by using the dispersion equation, the influence of the thickness of the triangular element and the electromagnetic parameters of the combined model on a surface wave attenuation constant is discussed, and a surface wave attenuation constant model based on three-dimensional reconstruction of damage of the wave-absorbing coating is constructed. The application provides a theoretical basis for damage evaluation of a wave-absorbing coating of an aircraft.

The present invention relates to the technical field of tire simulation design, and particularly to a method, a system and a computer software product for quickly dividing a complex tire tread grid. The method includes: dividing a planar graph of the tire tread into grids, and dividing the tread area into quadrilateral or triangular elements; drawing contour curves according to the tire tread contour, including the tread curve, the bottom curve of the tread groove and the bottom curve of the tread; generating node and element information of the planar graph, and projecting the planar nodes onto the tread curve to construct three-dimensional node coordinates; projecting the tread nodes into the interior of the tread, and generating internal nodes by using the intersection points of the node normal vectors and the contour curves; finally generating a three-dimensional element structure, thereby forming a three-dimensional grid division. Compared with the traditional method, the present invention does not rely on three-dimensional modeling, can significantly improve the grid division efficiency, reduce the calculation cost, and is applicable to the accurate simulation analysis of complex tire treads.

The present invention relates to a method and device for processing three-dimensional images that allows distortions to be minimised in a sensor measuring the direction of a signal from a source and that comprises the steps of: providing one or more measuring sensors for measuring a signal coming from a source, the sensors being associated with one or more spatial positions, wherein the measuring sensors are configured to obtain a direction of the measured signal with respect to said spatial positions; breaking down the sensor into one or more locations; generating one or more geodesic spheres in each location, wherein each geodesic sphere comprises a set of triangular elements with vertices that are almost evenly spaced apart; encoding a signal representative of the direction between the centre of the sphere and the position of the source in a set of vertices of the sphere; and generating a vector associated with each vertex, to store information about the signal intensity.